Single ended, quartz type incandescent lamp



Nov. 7, 1967 E- GATES 3,351,802

SINGLE ENDED, QUARTZ TYPE INCANDESCENT LAMP Filed June 12, 1964 PAUL E. GATES INVENTOR.

TT EY United States Patent 3,351,802 SINGLE ENDED, QUARTZ TYPE INCANDESCENT LAMP Paul E. Gates, Danvers, Mass, assiguor to Sylvania Electric Products Inc., a corporation of Delaware Filed June 12, 1964, Ser. No. 374,750 4 Claims. (Cl. 313-315) This invention relates to incandescent lamps having quartz envelopes and a fill of halogen. Particularly this invention relates to such lamps having single ends, that is having both lead-in wires extending from the same end of the lamp.

In the prior art, quartz-iodine incandenscent lamps have been constructed in a tubular shape with an axially extending filament. Press seals were made at either end of the tube and lead-in wires to the filament extend therethrough. Although such devices have fulfilled many needs, the art has required miniaturization. With the necessity for smaller lamps, the industry has turned to single ended construction. With such lamps, both lead-in wires extend through the same end of the envelope and hence, can be adapted to standard screw-type bases, if desired. Incandescent lamps having quartz envelopes and containing quantities of iodine are known to the art. Such lamps operate on a tungsten-iodine cycle which is a regenerative, continuing process in which tungsten iodide is produced when the iodine combines chemically with particles of tungsten evaporating from an incandescing tungsten filament. Subsequent thermal decomposition of this compound replaces the tungsten particles on the filament. In conventional filament lamps not containing controlled quantities of iodine, these particles are deposited on the envelope thus gradually causing a loss of light due to blackening. Rupturing of the filament may occur when a sufficient quantity of tungsten particles evaporate and then the lamp must be replaced. However the tungsteniodine cycle eliminates lamp blackening and reduces lamp outage by its getter action.

The iodine, together with the heat of the lamp, prevents the tungsten from accumulating on the lamp envelope and darkening it. As the vaporized tungsten iodine circulates back into the area of the incandescent filament, the intense heat of filament frees the tungsten from the tungsten iodide by thermal decomposition and tungsten is deposited back of the filament, leaving the iodine free to begin a new cycle. Theoretically, if the evaporating tungsten particles could be returned to the filament in a perfectly even coating, the lamp might never burn out. But since there is no way to control exactly where the tungsten particles return to the filament, one spot will eventually wear out, thus rendering the iodine-quartz lamp inoperative. This condition, however, appears after operation in the order of hundreds of hours and possibly even thousands of hours before lamp failure. Furthermore, during the life of an iodine lamp the maintenance of life output is substantially constant.

The usual method of preparing single ended quartz iodine lamps was to dispose a generally U-shaped filament within an envelope having a closed end. Each leg of the coil was attached to one side of a molybdenum'foil section and an external lead-in wire was attached to the other. An exhaust tube was attached to the closed end of the envelope in communication with the interior and during the sealing operation gases were pumped and filled therethrough. The quartz was softened and the sides were press-sealed around the foil sections and over the leg and lead-in wires.

When the press-seal was made the molybdenum frequently split, was left exposed or sometimes oxidized. Occasionally the filament was not centered properly after the seal was made or leaks from about the lead-in wires formed in the lamp. Most eminently with press seals, a residue of an exhaust tip was left upon the top of the envelope after the lamp was manufactured. The residue distorted the optical properties of the lamp which is highly undesirable.

According to my invention, 1 have discovered a seal construction which eliminates these problems and secures the further advantage of allowing substantially greater electrical current capacity. A multiplicity of molybdenum foil sections can be connected from lead-in wires to single coil legs so that large amounts of current can be carried into the lamp.

In order to manufacture the tipless incandescent lamps of my invention, a hollow, cylindrical stem support is formed with an axially aligned exhaust tube depending therethrough. A quartz glass envelope with a downwardly extending neck section is disposed around the stem support. interposed between the stem support and the neck of the envelope are the molybdenum foil sections, the lead-in wires and the filament supports with the filament extending into the envelope. In order to seal the envelope to the stem support, the quartz of the neck section is heated to softening and simultaneously the stem support heats also. When softened, a shaping tool is scraped around the glass and the two sections join together with the lead-in wire assembly interposed therebetween. Pumping and filling operations can be conducted through the internally extended exhaust tube and no tip need be placed on the top of the envelope.

Accordingly, the primary object of my invention is to seal the ends of lamps having quartz envelopes.

Another object of my invention is to reduce the number of lamps which are defective due to cracked molybdenum foil sections, imperfect seals, and oxidation of the metal parts.

The many other objects, features, and advantages of my invention will become manifest to those conversant with the art upon reading the following specification when taken in conjunction with the accompanying drawings wherein specific embodiments of my lamp having a tipless quartz envelope are shown and described by way of illustrative examples.

Of these drawings:

FIGURE 1 is a cross-sectional view of one embodiment of a tipless incandescent lamp taken along line 11 of FIGURE 2 and FIGURE 2 is a side elevational view of the lamp.

FIGURE 3 is a cross-sectional view of another embodiment of a tipless incandescent lamp taken along the line 3-3 of FIGURE 4 and and FIGURE 4 is a side elevational view of the lamp.

FIGURE 5 is a view of a means for increasing the current carried into the filament of the lamp through the seal in the lamp envelope.

Referring now to FIGURES 1 and 2 of the drawing, the lamp includes a generally tubular quartz glass envelope 1 having a neck section 2. Generally the neck section 2 has a lesser diameter than the envelope 1 although the relative diameters are not critical. Disposed within the neck section 2 is a tubular, quartz mount support 3 with a closed end and of a size and shape compatable with the neck section 2. The glass of the neck section 2 is sealed to the glass of the mount support 3. An exhaust tube 4 is disposed inside of the mount support 3 and its interior is in communication with the interior of the envelope 1. A fused exhaust tip 5 is disposed at the end of the exhaust tube 4 to seal the lamp from the atmosphere. The length of the exhaust tube 4 is not critical and the sealing tip 5 may be placed anywhere along its length. Generally, the mount support is formed by making a 3 hole in the closed end of the mount support 3 and then fusing an exhaust tube thereto.

A tubularly shaped envelope 1, neck section 2 and mount support 3 are prefused because they can be sealed together easily. Also, the lamp produced using such configurations has the generally accepted shape of lamps. The dimensions can be varied, however, to suit individual requirements for particular lamp shapes.

A pair of lead-in wire 6 and 7 are disposed in the seal between the neck section 2 and the mount support 3. Attached to the lead-in wires and within the seal are intermediate molybdenum foil sections 8 and 9. These sections are very thin, for example approximately 8 10 inch, and go into tension without rupturing or scaling 011 when the heated quartz cools. Supports and 11 for the filament 12 are attached to the molybdenum foil sections 8 and 9.

In manufacturing the lamp, the mount support 3 with an open exhaust tube 4, is mounted upon a glass lathe. A U-shaped assembly of lead-in wires 6 and 7 attached to foil section 8 and 9 and bridged by filament 12 with supports 10 and 11 is placed on either side of the mount 3. The neck section 2 is slipped over the mount 3 with the envelope 1 extending about the filament 12. While revolving the pieces, the glass in the neck is then heated until it becomes soft and a shaping tool is forced against it. The glass of the neck section 2 then becomes fused to the glass of the mount support 3. When fabricated and cooled, the normal pump and fill operation can be used to incorporate the necessary gases and ingredients. They will, however, be added through the exhaust tube 4 which can be sealed off with a tip 5 when completed. No exhaust tip need be visible on the envelope 1.

The lamps shown in FIGURES 3 and 4 vary from those in FIGURES 1 and 2 in that they are smaller and have an envelope of a different external configuration. The generally bulbous envelope 13 surrounds the filament 14 which is disposed upon support wires 15 and 16. Support wires 15 and 16 lead into the glass seal between neck section 17 and mount support 18. Molybdenum foil sections 19 and 20 are attached to the filament supports 15 and 16 and are also disposed within the glass seal. Lead-in wires 21 and 22 are attached to the molybdenum foil sections and outside of the lamp. Fabrication and sealing techniques are similar to those described previously. With either of the lamp types described previously, a conventional screw-type base can be attached to the base. Such disposition enables easy interchange of the lamps in fixtures as desired.

Frequently it is necessary to increase the current across the filament. In order to increase the current, two molybdenum foil sections 24 and 25 can be tied together in parallel and attached to one leg 23 of the filament as shown in FIGURE 5. A branching lead-in wire 26 can be attached on one end to a single lead-in wire 27 and on the other ends to the foil sections. Similar parallel arrangements can be disposed upon the other leg of the filament.

(C) CHEMICAL It is appetaoinshrdlcmfwypvbgkqjhb It is apparent that modifications and changes can be made within the spirit and scope of the instant invention but it is my intention, however, only to be limited by the appended claims.

As my invention I claim:

1. An incandescent lamp comprising: a tipless quartz glass envelope; a neck section disposed at one end of said envelope; a mount support disposed within said neck section and sealed to said neck section, said mount support having a closed top; means forming an aperture in said closed top; an exhaust tube sealed at one end and disposed within said mount support and attached to said means, the interior of said tube being open at the other end and in communication with the interior of said envelope; a filament disposed within said envelope; two means to conduct current from an external source through said seal and to said filament.

2. The lamp according to claim 1 wherein said neck section and said mount support are cylindrical.

3. An incandescent lamp comprising: a tipless quartz glass envelope; a cylindrical neck section disposed at one end of said envelope; a cylindrical mount support disposed within said neck section and sealed to said neck section, said mount support having a closed top; means forming an aperture in said closed top; an exhaust tube sealed at one end and disposed within said mount support and attached to said means, the interior of said tube being open at the other end and in communication with the interior of said envelope; a filament disposed within said envelope; two means to conduct current from an external source through said seal to said filament, each of said two means to conduct current being a pair of molybdenum foil sections disposed in the seal to said neck section and a pair of lead-in wires each of which extends from the outside and is attached to the foil sections and a pair of support wires, each of which extends from the foil sections and is attached to the filament.

4. An incandescent lamp comprising: a tipless quartz glass envelope; a cylindrical neck section of smaller diameter than said envelope disposed at one end of said envelope; a cylindrical mount support disposed within said neck section and sealed to said neck section, said mount support having a closed top; means forming an aperture in said closed top; an exhaust tube sealed at one end and disposed Within said mount support and attached to said means, the interior of said tube being open at the other end and in communication with the interiorof said envelope; a filament disposed within said envelope; two means to conduct current from an external source through said seal to said filament, each of said means being a pair of molybdenum foil sections disposed in the seal and a pair of lead-in wires, each of which extends from the outside and is attached to the foil sections and a pair of support wires, each of which extends from the foil sections and is attached to the filament.

References Cited UNITED STATES PATENTS 2,159,794 5/1939 Hagen et al 313220 2,169,112 8/1939 Scott et al 313--220 X 2,904,716 9/1959 Malm et al 313-318 3,048,741 8/1962 Thouret 3 133 10 X 3,132,278 5/1964 Collin et al 3l3-222 X 3,227,909 1/1966 Schilling et al 313315 FOREIGN PATENTS 476,833 12/1937 Great Britain.

JOHN W. HUCKERT, Primary Examiner. A. J, JAMES, Examiner, 

1. AN INCANDESCENT LAMP COMPRISING: A TIPLESS QUARTZ GLASS ENVELOPE; A NECK SECTION DISPOSED AT ONE END OF SAID ENVELOPE; A MOUNT SUPPORT DISPOSED WITHIN SAID NECK SECTION AND SEALED TO SAID NECK SECTION, SAID MOUNT SUPPORT HAVING A CLOSED TOP; MEANS FORMING AN APERTURE IN SAID CLOSED TOP; AN EXHAUST TUBE SEALED AT ONE END AND DISPOSED WITHIN SAID MOUNT SUPPORT AND ATTACHED TO SAID MEANS, THE INTERIOR OF SAID TUBE BEING OPEN AT THE END AND IN COMMUNICATION WITH THE INTERIOR OF SAID ENVELOPE; A FILAMENT DISPOSED WITHIN SAID ENVELOPE; TWO MEANS TO CONDUCT CURRENT FROM AN EXTERNAL SOURCE THROUGH SAID SEAL AND TO SAID FILAMENT. 